Lancaster Bomber night raid art print. The Avro Lancaster Bomber was a World War II heavy bomber made for the British RAF. The lancaster bomber first saw active service in 1942 and specialised in night time raids. The most famous sorties where against the Rhur Valley Dams, depicted in the film The Dam Busters. Over 7,300 Avro Lancaster Bombers were built during the second war war. Today there are only two remaining Lancaster Bombers left flying, one in the UK and one in Canada. A further 15 are in museums.